Flexible plastic containers are commonly used in the medical field for a wide variety of applications such as to store and deliver therapeutic fluids to a patient or to contain cells that are being grown in a cell culture medium. The plastic containers typically have a front and rear panel that are sealed along their lateral edges to define an aseptically sealed containment pouch. Access is typically provided to the containment pouch through a fluid conduit such as tubing that extends from outside the containment pouch to interior of the containment pouch. The tubing is sealed with a membrane or elastomeric septum to maintain a sterile environment. On a side of the container opposite of the access tubing is a hanger hole so that the hanger may be suspended from a hanger or a load cell.
It is possible to grow suspension cells (anchorage-independent cells) or adherent cells (anchorage-dependent cells), in vitro, in flexible plastic containers such as those disclosed in commonly assigned U.S. patent application Ser. No. 08/330,717. The cells are grown in a cell culture medium contained within the flexible container and the container is placed inside an incubator. It is possible to use aliquots taken from a container of cultured cells to start numerous other cell cultures. This process, known as cell subculturing, increases the rate of growth of the cells.
Cell subculturing requires transferring an aliquot of the cultured cells contained within one container to a receiving container or numerous receiving containers and diluting the aliquot of cultured cells in each receiving container with a cell growth medium. The cell growth medium provides the necessary nutrients for the cells to grow. A method and apparatus for subculturing cells is disclosed in commonly assigned U.S. Pat. No. 4,937,194 ("'194 Patent"). The '194 Patent discloses fluidly connecting in series a cell culture container to a container having cell culture medium and eventually to a receiving container or numerous receiving containers. The '194 Patent discloses using a metering device including, for example, a burette (FIG. 1), a roller pump (FIG. 2), a container having a fixed volume, or a syringe (FIGS. 3 and 4) to provide the desired amount of cell growth medium to dilute the aliquot of cell culture.
While the '194 Patent discloses a method and apparatus for aseptically connecting a cell culture container to multiple receiving containers, the metering device and method used are labor intensive and require continued operator attention.
U.S. Pat. No. 5,240,854 ("the '854 Patent") also discloses a device and method for the subculturing of cells. The device includes an array of growth chambers enclosed within a vessel. The growth chambers are defined by an array of stacked plates having a peripheral wall. The plates are welded together along the peripheral walls of one plate to a groove in another plate by ultrasonic welding or solvent bonding or other technique to form a fluid tight seal between the plates. The stacked plates form cell Growth surfaces. Cell culture and cell growth media are supplied and removed from the plates through an inlet fluid conduit and manifold and an outlet fluid conduit and manifold.
Because the '854 Patent requires that the cell growth plates be welded together, it makes access to the cells difficult as one has to cut open the vessel to inspect the cells. (Col. 8, lines 52-55). Further, because the plates are housed in a vessel, they are apparently not subject to visual inspection through a microscope or the naked eye.
Other methods for subculturing cells requires a solution transfer pump to transfer the desired amounts of the cell culture and cell culture medium to a single receiving container. A solution transfer pump typically has numerous rotors each rotor having a separate fluid inlet that may be connected to separate containers. The solution transfer pump is capable of transferring fluids either simultaneously or sequentially from these separate containers to a single receiving container. In particular for cell subculturing, a cell culture container and a container of cell growth medium are connected to separate pump rotor inlets. A receiving container is fluidly and aseptically connected to an outlet side of the solution transfer pump. To transfer the desired volume of the cell culture and the growth medium, the receiving container is suspended from a load cell on the solution transfer pump which allows the volume of liquid transferred to the receiving container to be determined gravimetrically.
Using a solution transfer pump in this fashion provides several disadvantages. Only one receiving container may be hung from the load cell and thus only one receiving container may be connected to the solution transfer pump. Thus, in instances where a cell culture is to be divided into numerous receiving containers, each fill operation requires an operator to form an aseptic seal upon attaching and detaching the receiving container to the outlet of the transfer pump. This is a time consuming process which, in many instances, takes longer than the time required to transfer fluids to the receiving container. Further, each seal operation presents the risk of contaminating the cell culture.
Each of these filled receiving containers must then be immediately transferred to an incubator to continue the cell culture process. Thus, multiple trips must be made in transporting the filled receiving container to the incubator which increases the possibility that one of these containers may be damaged by dropping it or otherwise. Each trip to the incubator also increases the time to complete the subculture process. Minimizing the fill time is critical to the viability of the cell culture supply as the cell culture supply is outside the incubator and exposed to outside environment temperatures and potential contaminants.
Using a receiving container as described above having an access tube on one end of the container and a hanger on the opposite end creates further problems when used with a solution transfer pump. Because the container is suspended from the hanger to the load cell, the access tubing is necessarily on the bottom of the container. Thus, the solution transfer pump must fill the container from the bottom up. This increases the back pressure on the pump as the pump has to force fluid upward against the force of gravity and against the fluid in the container. Filling from the bottom up may also lead to uneven filling of the container.
In accordance with the present invention an apparatus, system and method of transferring fluids from one or more containers to numerous containers are provided using a solution transfer pump. The invention is particularly useful for fill operations such as the subculturing of cells and hospital pharmacy fill operations, where the fluid transfer must be performed aseptically. The invention when used for the subculturing of cells should decrease the number of cultures lost due to a break in aseptic conditions and should decrease the time required to complete a fill operation.